In a centrifugal separator, the separation of solids from the liquid is commonly accomplished by pumping the contaminated coolant or liquid into a high speed rotating chamber or bowl. The centrifugal gravitational forces created by the high speed rotation of the chamber cause the contaminated fluid to conform to the interior outside vertical surface of the rotating chamber. Since the chamber is rotating at a high speed, the solid material is forced to adhere to the side of the bowl or chamber while the cleansed coolant or liquid exists through openings commonly located at the bottom of the bowl to be drained away through an outlet pipe. Automatic cleansing systems have been provided, wherein scraper blades mounted inside the rotating bowl are activated to automatically scrape or plow the solids from the side of the bowl and expel them into a sludge container mounted below the unit.
One improved apparatus provides for enhancing the operation of a centrifugal separator and automatically adjusting for varying amounts of solids in contaminated fluid being passed through the separator. This includes a load sensing circuit which monitors the load on the drive motor of the separator centrifuge bowl and signals for a cleaning cycle based upon the load information. Another centrifuge uses an inverted filter. Dewatering is accomplished by pressurization and displacement of liquids through a packed filter bed. Wet solids then are removed from the filter bed.
Despite these improvements, the scraper blades are hard to clean as wet solids stick to the blades. Filter cloth and packed filter beds have their own inherent set of clogging problems. Moving fluid through a packed filter bed and filter cloth demands high pressure and often is not efficient.